Transmitting multiple different signals on a polychromatic beam of light by using a different wavelength for each of the signals is generally referred to as wavelength division multiplexing (WDM). In order to recover the multiple signals once the polychromatic beam has been transmitted, demultiplexing techniques are used. Demultiplexing techniques are operative to spatially separate the different wavelength component signals so as to be able to recover the multiple different signals transmitted on the polychromatic beam of light.
Conversely, in order to combine a plurality of wavelength component signals into a single polychromatic beam of light, multiplexing techniques are used. Multiplexing techniques are operative to combine multiple wavelength component signals back into a polychromatic beam of light such that multiple signals can be transmitted on a single optical signal.
Multiplexers/demultiplexers are typically used in order to perform these multiplexing/demultiplexing techniques. Conventional multiplexers/demultiplexers are typically either diffractive (using diffraction gratings or array waveguide gratings), dispersive (making use of monolithic prisms for example) or use interference (for example interference coatings) to separate and recombine wavelength component signals. In addition to the examples mentioned above, there are several distinct mechanisms for achieving the diffraction, dispersion and interference effects. However, a deficiency with conventional dispersive multiplexers/demultiplexers is that they provide weak dispersion. As such, in the case of demultiplexing, the weak dispersion means that upon completion of the separation of the wavelength component signals from the polychromatic signal, the wavelength component signals are still quite close together, which causes them to be difficult to capture. This in turn makes the signals contained on each wavelength component optical signal difficult to recover.
Accordingly, there exists a need in the industry for an improved multiplexer/demultiplexer for causing the spatial separation of wavelength components of a polychromatic beam of light.